This invention relates to underwater diving equipment and more particularly to an improved exhaust valve for the controlled venting of spent or excess breathing gas from a diving helmet or mask.
Diving suits or rigs have commonly been provided with exhaust valves, usually mounted on the helmet, that serve in the nature of a one-way, or check valve, to prevent entry of water while permiting exit of gas from the suit when pressure therein exceeds a predetermined differential between the surrounding water pressure and that existing in the suit. These valves have typically been adjustable by the diver to select a pressure differential that will afford the best compromise between factors of bouyancy, freedom from squeeze by the suit, and adequate ventilation.
Additionally, exhaust valves are often provided with an override feature in the form of a button that the diver can press with his chin or head to quickly open the valve wide in the event it becomes necessary to rapidly dump air to make the suit heavy, as when in danger of a "blow-up," or when it is necessary to greatly increase ventilation, for example to clear carbon dioxide build-up from the suit.